如何在/ if中運行選擇SQL語句？

Question

我很難找到語句的語法（或者甚至可能）。

我們正在運行SQL Server 2005，我想這樣做：

IF ((SELECT count(*) FROM mytable WHERE userid = 'myid' AND value = 3) < 1) then INSERT INTO mytable VALUES ('myid', 3)

有什麼建議？由於

Answer 1

IF ((SELECT count(*) FROM mytable WHERE userid = 'myid' AND value = 3) < 1) 
BEGIN 
    INSERT INTO mytable VALUES ('myid', 3) 
END 

IF/ELSE reference

，或者您可以使用NOT EXISTS

IF NOT EXISTS (SELECT * FROM mytable WHERE userid = 'myid' AND value = 3) 

Answer 2

DECLARE @COUNT int 

SET @COUNT=(SELECT count(*) FROM mytable WHERE userid = 'myid' AND value = 3) 
IF (@COUNT < 1) 
BEGIN 
    INSERT INTO mytable VALUES ('myid', 3) 
END 

Answer 3

你可以試試這個做在一個聲明：

INSERT INTO mytable 
SELECT 'myid', 3 
WHERE (SELECT count(*) FROM mytable WHERE userid = 'myid' AND value = 3) < 1